Construction and manufacture of cinematograph positive films



Mrch 27, 1928. 1,663,738

\ J. E. THORNTON OONsTRUOTION AND NANUFAOTURN OF OINEMATOGRAPH POSITIVE FILMS Filed Dec. 15.. 1924 s sheets-sheet 1 Fig?.

7 f af/ March 27, 1928.

J. E. THORNTON CONSTRUCTION AND MANUFACTURE OF CINEMATOGRAPH POSITIVE FILMS 3 Sheets-Sheet 2 Filed Dec. 15,

Fglf.

| N V EN T0 R March 27, 1928. 1,663,738

J. E. THORNTON CON.`TRUCTION AND MANUFACTURE OF CINEMATOGRAPH POSITIVE FILMS Filed Dec. 15, 1924. 3 Sheets-Sheet 3 l b w/ 133%@ B5 Fig.

l-NVENTOR. ov.OsM/m. E

Patented Mar. 27, 1928.

UNITED STATES PATENT OFFICE.

JOHN EDWARD THORNTON, OF WEST HAMPSTEAD, LONDON, ENGLANE.

implication filed December 15, 1924, Serial No. 756,168, and in Great; Britain .Sanitary E?, w25.

This invention relates to improvements in the construction and manufactureof cincmatograph films.

lin the manufacture ot composite cinematograph films from two thin film strips it has been proposed to join them back to back (Celluloid to Celluloid) by applying a solvent of Celluloid to one or both backs and in a similar way to cement the Celluloid back of one to the colloid face of the other, butthe joining of two eolloid faces together by a celluioid varnish or by a solution of gelatine or glue has not proved permanently satisfactory.

lhe object of the invention is to provide a durable and permanent joint between 'the colloid faces of the two thin constituent parts of the ihn and consequent thereon a better and more durable cinematograph positive film in which tlie printed images will have a longer wearing life.

lThe tremendous strains, and thev instantaneous jerks and changes of position which a cinematograph film has to undergo during almost Continuous use and. running in a pro jector, preclude all possibilit-y of any gelatine-face-joint between two films holding permanently, unless one part is literally welded to the other part, so that they become virtually one, which is what I effect by this process.

According to the invention the colloid surfaces of the two' ilmsare prepared and rendered receptive of the jointing cement by roughening or graining or otherwise, to ensure that the cement layer will permanently interlock or amalgamate with the film surface partially physical and 4partially mechanical, and a fusible Cement is applied to the surfaces of the film strips wlnch will form a temporary joint and heat and pressure are applied to fuse the cement and cause it to fiow in to the interstices of the prepared surfaces.

The invention is illustrated in the accompanying drawings.

Fig. l. is a diagrammatic perspective View of a completed positive film.

Fig. 2. is a longitudinal section of one thin film drawn to a highly magnified scale.

Fig. is a longitudinal section of com- ,'pleted film showing joint between two films.

Fig. 4. is a diagrammatic view of means for uniting the two thin films.

Fig, 5. is a similar diagrammatic view showing a modification.

ln the drawings l. is a thin transparent base of Celluloid or other waterproof material. 3 is a layer of printed colloid, the printed images being shown more or less opaque, with a roughened and pitted or recessed face. 2 is adhesive substraturn. which indissolubly unites layers l 3. Jand 4 is a thin layer of fusible cement interloclred into the roughened face of the colloid layer 3. A

Fig. 4. Shows one method of bringing and uniting the two thin films together after having been roughenedv and cemented. hereinbefore described.

rlhe two films fr, AY-

in the assen-a bling machines from th respective spools with their faces coated with fusible cement .which is surface dry and therefore can be ternately and enga ing alternately with the .holes in the ot er sprocket. the sprockets revolve in the direction 'oit the arrows the films are first accurately pesi` tioned by their teeth which enter the i2orations of the films and as the sprockets further rotate the films are nipped between the peripheries of the 4slightly heated sprockets and thus lightly joined together. The pro cess is completed by the heavier pressure given by the pair of heated blocks B1 or B2, which open and close alternately so that whilst one is clamping, the other is opening or closing. This movement is effected by eccentric or crank motions (not shown), the Shanks of the blocks sliding in collars or bearings (not shown). The two sprockets S, S1 are geared together. After emerging from the lower blocks the films then pass between a pair of lamps D, D1 by which the insolubilizing action that renders the cement non-fusible is started by the exposure to light thus made.

Fig. 5. shows another method. The thin perforated films A, A1 are drawn by the teeth, of the sprockets S, S1 which enter the films and accurately position them. The heated blocks B3 then hold them, each film on a block, by two pins b, b1, and then advance clamp the a t and luso the cement, the pins oir each block entering the holes et the other block. At the nent step the blocks BS open but the nlm is previously caught and clamped by another pair et plain (painless) bloclrs h4 (like B2) and the tllins pass between the lamp l), D1.,

vkllhe colloid surlace oitv each oit the lin strips may be roughened, pitted or toothed either mechanically or chemically until it presents a yast number oit exceedingly minute points or teeth with depressions or minute deep recesses between. l

Zl/echcmcal nothing/.ellis roughening or teething process may be carried ont mechanically by passing the printed film whilst in a dry state between milling rolls, one oil which is plain and the other et which has been prepared by sand-blasting or in any other way that will give it a iinely milled or roughened grainy surface. 'llhis milled surface is again imparted te and reproduced upon the surface the eect ofv softenin oi the printed hlm by the ,operation oi? rolling under considerable pressure.

ln the ordinary way this milling of the surface of the nlm-print produces a groundglasy'eect so thatthe picture appears upon a translucent instead of a transparent nlm, but this translucency is removed and transparency restored by the superimposed layer lof transparent cement.

Uz/emz'cal to'ofhtngrllhe roughening or teething process may be carried out chemically by etching, which is the method at presentpreferred. l

A suitable etching solution is composed of calcium chloride and potassium ferricyanide and water. stated, because they require to be varied according to the make and kind of gelatine used, but as a guide 5 ounces of calcium, 5 ounces of ferrie anide, and 100 ounces of water may be ta' en as approximate gures. Other chemicals such as zinc-chloride, calcium-nitrate, ferrie-chloride, or sodiumchloride are each useful. The etching solution is applied to the dry surface of the lm strip. y l

Softemhig the colloz'd swlfce.-The nlm is :further treated by passing it through an alkaline bath such as a dilute solution of ammonia or caustic potash. 'This bath has theghard surface and o ening the pores o the gelatine, thus ena ling the liquid cement to more easily penetrate the rinted colloid and become better interlocked therewith.

Applying the @sneeuw-The second step of the process is to apply to the roughened or toothed surface of the printed film an exceedingly thin layer of the cement, which is made up as a very dilute solution, the composition ci which is hereinafter more speeically described.

This solution will a lication of theA pp ment will have partially or almost wholly No exact proportions need be p anintegral part 'underlying embraces the following elementary condi-I ow into all the hollows incarne ol the thed sartene, and alter its application the coating is dried, preferably slowly, in a dust-*iltered drying room.

` ilst goed results may be obtained with only one application of a relatively concentrated solution oi the cement, it is better to use a, more dilute solution 'and attain the desired thicess by applying two or three I 'l or even morev coatings, allowing each one to dry before the next is applied. 'lhe process can be carried out as a continuous operation,

'by apparatus which applies the several coatings at diderent points oil the same strip simultaneously, the iilm passing from coating apparatus to drying chamber in alternate succession. ln principle better results are obtained troni a succession of extremely thin layers than from one layer oil the same total thickness.

Effect of tf1/e cement coating- Upon examination ol the tilm `after drying it will be found that the coating o cement which has dowed into the hollows has so'contracted in the drying process that it has become tightly shrunk upon each one of the vast number of teeth or raised points, and has therefore become mechanically arnalgainated with the printed hlm.V At the same. time, owing to the softened state of the surface of the colloid image-layer, the dilute solution of cepenetrated the colloid layer by means of its opened ores, and the first of the dilute layers o cement will therefore have also physically amalgamated with and become practically a part of the printed colloid layer itself.` The next layer-of cement applied with the first layer, and-so on with each layer applied; so that the final result is that the cement layer itself, and throughout its entire thickness, becomes to all intents and purposes of the printed colloid layer. N amm of the y cewwnt.-The principle thev composition of this cement tions in the character of the cement z- A) It must be very tenacious.

B) It must bev very flexible and remain t permanently flexible.

' (C) It must be fusible or liqueiable by the application of heat beforetlie joint 'is finally made, Y

(D) It must be capable of solidiication after the liquefying process, by the application of cold-or a lower temperature.

(E) It must be capable of automaticr selfinsolubilition at the nal stage of the process after t e joint has been made.

These conditions can be met whilst allowing considerable variations inthe composition of the cement, but the principles governing these conditions are satisiied by a combination of the following factors 1 (A) The basis of the cement isl preferably enetrates and amalgamates in like manner a Very good quality of glue or fish-glue and a small proportion of glacial-acetic-acid; this will produce a cement of great tenacity;

(B) Flexibility is secured by incorporating a small proportion of glycerine, treacle, sugar, or equivalent hydroscopic-maintaining ingredient;

(C) Fusibility is secured by incorporating a small proportion of treacle, sugar, glycerine, or equivalent, hydioscopic-inain taining ingredient;

(D) Solidification upon cooling will resultfrom a mixture combining A, B, and C;

(lil) Gradual insolubilization is secured by incorporating a small. proportion of a bichromatc salt, such as ammonium or potassium bichromate, to be acted upon by light; or chrome alum or an e uivalent salt which will gradually react wifliout light.

No exact proportions need be stated, as the quantities of each must be Varied to suit the particular colloid used and the condition of its surface, but the following example may be taken as approximate proportions in an average case, to be adjusted as necessary Ounces or parts. Best quality pale glue 10 Glacial acetic acid 5 Glycerine 5 Golden syrup treacle 5 Ammonium bichromate 1 Water 100 The glue is soaked in 90 parts of water until soft, then melted by gently heating, in a jacketed vessel, and the glycerine and 4treacle are next added gradually and with fects. For instance vfish-glue, gelatine, ory

isinglass may be substituted for glue; sulphuric, nitric, or hydrochloric acid may be substituted for glacial acetic acid; sugar may be substituted for treacle; chrome alum may be substituted for bichromate; the proportions in each ease being adjusted to suit these alternative ingredients. All these alternatives are good substitutes, but those first hereinbefore named are referred.

Apply/ng he cement to t e )three-.Before ap lication of this cement the colloid faces o the two films are softened and the pores of the colloid opened as already described, taking care the process is not carried so i'ar as to unduly soften or dissolve the colloid layer. The cement is then applied only just warmes a coating in an exceedingly thin layer to each film, and it will partially penetrate and be absorbed by the softened printed colloid as already described. 'It is next dried, and the applica-s tion 'may be repeated two or three times with good effect, being again dried between and after each coating.

The assembling and registering operart2'0ns.-The two films are now ready for uniting. ln their dry condition the two iilms are accurately superimposed face-toface by means of an assemblin@f machine, provided with registration pins which exactly fill the holes in the two films; the two lms are automatically positioned by the machine so that the corresponding parts of' each film are correctly assembled and registei-ed upon the same pin.

Fusz'ny anni welding the wo colloid faceta- At the next step the two films are automatically clamped, with considerable pressure, between two metal blocks, in the form of a fixed bed and movabley platen which have a parallel motion towards and away from each other, Both blocks are heated by steam, gas, or electrical means, but preferably electrical.

The heat of' the two blocks slightly melts the two coated surfaces of cement, owing to the glycerine and treacle contained therein; and, owing to the extremely adhesive character of the cement when slightly melted by heat, the two surfaces are therefore joined by amalgamation of their two slightly melted adhesive coatings (which are in turn already interlocked with their printed colloid layers by penetration and by teeth) and after setting and cooling of the cement become virtually like one; in fact the t'wo films are in this manner literally fusedv or welded together. The duplex film is next cooled by being withdrawn from the two blocks and passed under a draught of cold air furnished by a fan.

An alternative means of' applying the necessary heat and pressure is to pass the films between rolls, heated electrically or otherwise, and provided with suitably shaped and accurate sprocket teeth for reg1stration purposes. One set is used to give the first uniting pressure, and further rolls (with or without teeth) to apply pressure over a sufficiently long period to complete the fusing and cooling process'.

Flat pressure is however preferred, rather than rolling pressure, as more conductive to accurate registration. But the flat and roll systems can be used in combination with useful advantages.

Another important point in the joining process is that the operations, firstly, for accurately placing or registerlng the two section-films, and then, secondly, for imfifi mediately. afterwards accurately uniting the two surfaces, should be effected in step-byvim 'following measures are impossible.

step or picture-by-picture manner hyinteimittent steps rather than by a continuous rolling action, in order to ensure the highest possible degree ot accuracy in superimposition oit the two lms.

Insolabileing the cement of lite joint- Previous to this operation the layer oi cen ment, now cold and solidiiied, still remains ilusible under the influence oit heat, and theretore might possibly come apart owing to the heat ol lamp in the projector; but the taken to make 'that The joined two-ply tilm rst receives a short exposure to light by beingkpassed be tween a pair ot mercury lamps, placed to act one upon each side oit tlie'tilm through itsx outer protecting celluloid covers or windows. Therefore at this stage the bichromate combined in the cement comesinto play, for the moment that the cement is quite dry the reaction of the bichromate, having first been started by the exposure ofthe film to light,v

steadily proceeds untilA it causes the cement to become a completely insoluble and therefore non-fusible body.

This recess' of insolubilization, which is a continuing one, prevents any possibility of the cement ever being re-fused bythe heat ofthe lamp in the projector coloring produced is insuicient toma e any color or trans.

appreciable difference in the parency ofthe Vpicture-image An alternative means for effecting the insolubility without lany;coloration whatever,

is to substitute a small quantity of chromev ,v l

' the film is complete and finished is also desir;

alum for the bichro'mate, and to dispense with the light action. In that case also the joint will automatically become a permanent one,owing to gradual insolubiliz'ation of the cement by the chrome alum. This process will `however take a very much longer time to 'effect complete. insolubilization. Forma- 1in might poss1bly be substituted for chrome pressed air, operating one upon alum, and also other possible equivalents.

,. Keeping the perforatz'o-m cleaner-In applying the cement to the colloid faces it.s necessary to ensure that it does lnot leave the perforations with thincovers of dried cement. rlhis is effected' by passing the cement-coated7 film between two jets of comand one upen theitront ot the iilm-strip, as it leaves the coating apparatus, the jets being placed not opposite but one in'advance ot the other, so that as the lm travels past them any cement' that has crept int/o the holes is blown clean out,vby air-jets acting then from the othen' have been finally united lirst from one side Alter the ilms (which 'wouldv y"crine bath before lthe cement is applied cause the joint tocone apart) on lthe conthe back v henares rieten@ @me mamey 0f he completen Flemlbz'lty of. the completed rileva-The question of dexibility oi the inner core corn prising the colloid image-layers and the cementing layers is of extreme importance. Unless suitable proyision is made to ensure flexibility the gluing together of the two films would result in a ilm too stili and too indexible. U

`This* condition is howeversatisfactorily met by the proportion of glycerine or treacle (or both combined) included in the cornposition of the cement. Ordinary sugar may be substituted for' treacle if preferred. A partfof this is absorbed by the printed colloid image-layers. Or if referred the colloid layers may be treate in a dilute glycthem, and the application may be made as a separate bath treatment or by incorporating the glycerine with the softening solution. It ldoes not matter at what stage the glyc- 'erine is'introduced so long as the respective layers contain suiiicient to maintain yflexibility and sutlicient to prevent absolute drying ofthe layers yet allowing of approximate surface dryness.

[nsolwbil'ty of all layers of the completed .--Total insolubility of all layers when able, but it must be associated with permanent flexibility. As already Splicing the emls of ifwo fllma 'llhe usual way oi joining the ends ot two tilms, known as splicing, is to remove (by a scraper) the icture-image colloid-layer of each tilm tor a out one eivhth ot an inch, and xthen join the twoV ends by applying Celluloid cement to the narrow bare portions, ,placing them to overlap, and pressing the two narrow bare Celluloid parts togethernntil the cement is dry.

described this condition ofV permanent flexibility is ensured by the presi lo Such a join or splice is always a sourceof trouble in using the film unless made with 'the utmost care; in any case it is always a short splice (usually about one eighth of an inch); and as one strip overlaps the other the film is thicker at the splice. i

in a two-ply film a much better splice can be made by making the celluloid back of one complete picture to join at the top mask-line division and the other celluloid back to jo1n at the bottom mask-line. Thus the splicing of the two thin Celluloid supports do not coincide but are separated by one picture space, ard a strong splice is made Without much increase in the films thickness at the splice. The splice therefore consists of two single-film layers and the total thickness 1s not as greatly increased as in the films now in use. n

A/iouotlier form of join or splice which can be made only in filmsv made according to this invention is effected by placing between the two films, for a length of say one or two pictures of each of the two ends to be joined, a`

thin splicing-liner consisting of a strip of very thin Celluloid coated upon each side with a thin layer of jointing cement. This splicing-liner is perforated, adjusted in position, and then heat and pressure applied to the entire joint, so that the two film-faces are adhered to the splicing-liner which is placed inside between the two films. Though such a splice makes the film slightly thicker than in the first example, it makes a much better and smoother and infinitely stronger form of join than theimethod at present used in standard film, andthe liner can be tapered ofll to a feather-edge at each end in the manufacture of the splicing-liner material.

The finished .somtchZess-v'fmage film.

When all the processes are completed the finished film-strip of ositive pictures will comprise a single-widt strip of perforated film of standard thickness, but with its images buried within its interior, and composed of the following layers arranged in the following order, but indissolubly amalgamated as one film (l) A base of celluloid or other transparent waterproof material, which forms firstly a Support for layers 2 and 3 of the unprinted film, and also finally, one of the outer covers of the completed film;

(2) An adhesive substratum superimposed upon the base,- and indissolubly uniting layers i and 3;

(3) A colloid layer superimposed upon the substratum 2, and having a series of complete pictures or parts of pictures printed thereon; the printed colloid having its face prepared for interlocking in the special manner herein' described;

(4) An exceedingly thin layer of special cement as herein described attached to such surface partly by impregnation of its pores and partly by interlocking with its surface teeth;

(5) An exceedingly thin layer of special cement as herein described, attached to the printed colloid surface 6 partly by impregnation of its pores and partly by interlocking with its surface teeth;

(6) A colloid layer superimposed upon the substratum 7 and having either a series of partial pictures complementary to and completing those on colloid layer 3; or alternately unprinted, plain colloid without pictures;

(7) An adhesive substratum superimposed upon the base and indissolubly uniting layers 6 and 8;

(8) A base of celluloid or other transparent waterproof material, which forms firstly a support for layers 6 and 7 of the unprinted film, and also finally the other outer cover of the completed film; the first film comprising layers 1, 2 and 3, being indissolubly united by its cement layer 4 to the cement layer 5 of the second film, which comprises layers 6, 7 and 8, by the application of heat and pressure until they are completely welded or fused together.

What I claim as my invention and desire to protect by Letters Patent is 1. A method or process of producing a cinematograph positive film which consists in printing upon and finishing two thin films, each of approximately half standard thickness, erparing the printed-colloid faces of both films to receive a cement, applying to the prepared printed-colloid-faces a fusible cement, temporarily joining the two films together and subsequently converting the temporary joint into a non-fusible permanent face joint by the application of heat and pressure to the films.

2. The process of attaching two thin positive films together which consists in preparing the printed-colloid-surfaces by forming thereon a vast number of minute projections and recesses applying thereto a fusible cement which will interlock therewith to form a fusible temporary joint and subsequently converting it into a permanent non-fusible joint by rendering the cement insoluble by the action of light.

3. In the production of cinematograph positive films the process of attaching two thin films together which consists in preparing the printed-colloid-faces by etching thereon by a chemical process a vast number of minute projections and recesses, and ap- 45 sponding section of each plying thereto a fusible cement which will interlock therewith, to form a 'fusible temporary joint and subsequently converting it yinet/o a permanent non-fusible joint by ren.-s

dering the cement insoluble by the action of light.

j t. lin the production of cinematograph positive films of two thin section films united face-to-face, the. process of attaching l@ the two thin lms which consists in softening and opening the pores of the printedcolloid-faces of the two thin films, producingfon the said faces a vast number of minute projections and recesses, amalgamating d a layer of fusible adhesive cement to and with the colloid faces by applying to each face a solution of the cement, allowing the cement to partially penetrate 4the opened pores of the colloid, and also attach itself to the roughened surface and become firmly interlocked therewith, to form a fusible temporary joint and subsequently converting it into a permanent non-fusible joint by ren.- deringthe cement insoluble by the action of light.

5. In the production` of cinematograph positive films united face-to-face, the process which consists in softening and roughening the printed-colloid-faces thereof, applying a solution of a fusible cement thereto to interlock with the said faces assembling the two thin films in correct order and position facetp-face, pressing the two lms together withsufiicient heat to fuse the cement upon both faces, and finally allowing the cemented film to cool and the cement to re-solidify.

. In the production of cinematograph positive films united face-to-faoe the rocess which consists in softening and roug ening the printed colloid-faces thereof, applying a solution of a fusible cement thereto to interlock with the said faces, assembling the two films in correct order and position faceto-face; accurately registering the correpicture clamping vpleted joint.

ineen/ee the films together betweenltwo metal bloclts which are suiciently heated to fuse the two cement layers; and finally allowing the cemented films to cool and the cement to resolidify; and repeating the process until the entire length of two lms have been joined fill by a series of step-by-step intermittent movements.

7. lin the production of a scratohlessimage positive film, comprising two thin section-films, united face-tofiface by an insoluble permanent face joint, and in the construction of such joint,'supplementing the process claimed in claim t by a process of insolubilization, by which the still fusible face-joint is converted into anv insoluble, non-fusible, permanent'one, by the reaction of a chrome salt upon the .glutinous colloid of the cementing material to effect a com- 8. In thev Vproduction of a scratchlessimage positivel film comprising two thin section-films, united face-to-face by an insoluble permanent face joint, and in the construction of such joint, supplementing the process claimed in' claim 4Lv by a process of insolubilization, lby Awhich the still 'fusible temporary face-joint is converted into an insoluble,nonfusible, permanent one, by the action of li ht upon a bichromate salt and glutinous co loid which form part of .the cementing material, to effect a very rapidly# completed joint.

9. A cinematograph positive film comprising inits construction two thin films of` cellulosic waterproof material, a roughened colloid printed surface on each thin film' laid face-t'o-face, and a flexible fusible cement with which is incorporated a hygroscopic ingredient and a chrome salt, between the faces of the two thin films by which they` are cemented together.

' In testimony whereof I have hereunto set my hand.

JOHN EDWARD THORNTON. 

